1. Field of the Invention
The present invention relates to walls, doors, lids, covers and other elements of industrial furnaces and the like that are formed from components subjected to high heat during use that are provided with chimney-like internal passages through which flows of ambient air are induced to circulate without being blown, pressurized or otherwise forced to flow, to perform a cooling function. Stated in another way, the present invention relates to methods and means for providing cooling flows of ambient air that self establish through interior regions of heated components of industrial furnaces and the like, by providing elongate chimney-like passages that extend internally through the heated components, with the passages defining inlets and outlets near opposite end regions thereof that communicate with a body of ambient air, and with the outlet of each passage being located higher than the inlet so that ambient air 1) may enter the inlet, 2) may become heated and rise in the chimney-like passage as the ambient air is exposed to the hot interior of at least one of the heated components, and 3) may discharge through the outlet so as to carry heat energy away from the interior of at least one of the heated components. The outlet end regions of the passages may be of greater cross-sectional area than the inlet end regions to encourage ambient air that becomes heated and expands within the chimney-like passages to discharge from outlets that are less restrictive than the inlets. If the passages are defined by conduits made from high heat resistant metal such as stainless steel, and if the conduits have central regions that are embedded within furnace components formed from cast refractory material, conduit end regions that project from the cast refractory components may be connected to a supporting framework, by which arrangement the conduits serve not only to cool the cast refractory components but also to mount the cast refractory components on the framework.
2. Prior Art
Industrial furnaces are well known that employ wall, door, lid and cover components that will provide improved service longevity if they are cooled during use to minimize the detrimental effects of a high heat environment. While efforts have been made to provide such components with coolant tubes through which flows of coolant (such as water or refrigerant) may be circulated by means of pumps, blowers, compressors and the like, these forced flow coolant systems have many drawbacks including complexity, high cost, and the need for active programs of maintenance to ensure that coolant circulates properly at times when the components are subjected to high heat.
Many components that are subjected to high heat (such as components that are used in forming walls, doors, lids and covers of industrial furnaces and the like) can be formed advantageously from castable refractory material. Normally castable refractory furnace components are held in place with the aid of metallic anchors that are positioned and oriented to favor (i.e., positioned near and/or extending toward) the cold face of the refractory components to ensure that the anchors remain as cool as possible. While these metallic anchors often are formed from stainless steel (to provide reasonably priced anchors that will offer relatively good resistance to high heat), the failure of these anchors in refractory systems that are exposed to high heat temperatures as high as 2800 to 3100 degrees Fahrenheit is quite common.
The complex nature of forced coolant flow systems that employ fans, pumps, blowers, or compressors together with coolant reservoirs and interconnecting coolant supply lines renders the use of forced flows of circulating coolant impractical and unworkable with many types of industrial furnace components. Thus, a long-standing need has existed for a much simpler method and means for cooling heated components of industrial furnaces and the like to lengthen the service life of these furnace components by permitting these components (and metallic elements that are embedded within many of these components) to operate at cooler temperatures.
The applicant, Gary L. Coble, is the named inventor in several patents that feature related subject matter. While many patents disclose industrial furnace components of a type that would benefit from the provision of a simple cooling method and means, U.S. Pat. Nos. 5,335,897 and 5,483,548 issued to Gary L. Coble provide good examples thereof, hence the disclosures of these patents are incorporated herein by reference. The manner in which cast refractory components are made and put to use in the bases of annealing furnaces is disclosed in U.S. Pat. Nos. 5,562,879, 5,575,970, 5,578,264, 5,681,525 and 5,756,043 issued to Gary L. Coble, and the disclosures of these patents also are incorporated herein by reference.